From 371e8e4cd79c3927f7aa2ca3aaef9c3da546c0fc Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E2=80=9Cjaketae=E2=80=9D?= <jaesungtae@gmail.com>
Date: Thu, 27 Feb 2020 06:53:51 +0900
Subject: [PATCH] Use defaultdict for optimization

---
 pandas/core/frame.py | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/pandas/core/frame.py b/pandas/core/frame.py
index 3fc10444ee064..b6b6a4fe74ed5 100644
--- a/pandas/core/frame.py
+++ b/pandas/core/frame.py
@@ -8446,9 +8446,8 @@ def isin(self, values) -> "DataFrame":
 
 def _from_nested_dict(data):
     # TODO: this should be seriously cythonized
-    new_data = {}
+    new_data = collections.defaultdict(dict)
     for index, s in data.items():
         for col, v in s.items():
-            new_data[col] = new_data.get(col, {})
             new_data[col][index] = v
     return new_data